1. Field of the Invention
The present invention relates generally to an oil level monitoring device for an automatic power transmission in an automotive vehicle.
2. Description of the Background Art
One example of a conventional oil level monitoring device for an automatic power transmission is disclosed in Japanese Utility Model First (unexamined) Publication (Jikkai) Showa 54-45878. The device generally comprises an oil filler tube extending from a transmission casing, and an oil level gauge insertable into the oil filler tube. The oil filler tube extends in an essentially vertical direction, to place the lower end thereof in the vicinity of a lubricant oil level of a reservoir. The oil gauge passes through the oil filler tube so that the lower end portion thereof may reach, and is dipped into, a lubricant oil reservoir. The checking of oil level is performed by pulling out the oil level gauge from the oil filler tube and by checking oil residing on the lower end of the oil level gauge.
As can be appreciated, in such a conventional oil level monitoring device, it is essential to provide an oil filler tube so as to permit the oil level gauge to access the lubricant oil in the reservoir. Therefore, space for installation of the oil filler tube becomes necessary. Such necessity sometimes reduces freedom in designing the transmission casing and bars reduction of size of the overall construction of the automatic power transmission.
On the other hand, in the modern automotive automatic power transmission, one of the most important tasks is reducing the unit size and overall weight. For this, the presence of the oil filler tube becomes an interfering factor in designing a reduced size automatic power transmission. Furthermore, providing the oil filler tube necessarily requires extra parts and assembling processes, with higher production costs.